1. Field of the Invention
The present invention relates generally to a wind-power generation system and a method of operating the same, and more particularly to a wind-power generation system with an over-speed protection and a method of operating the same.
2. Description of Prior Art
For the most popular wind-power generation system at present, an inverter is usually used to provide electric energy with fixed frequency from the generation system to a power grid. Because the used equipment and electric machinery are often more expensive and difficult to be replaced in a large-scale wind-power generation system, the reliability of the generation system and the inverter becomes more important. In addition, the large-scale wind-power generation system is usually used in bad climatic and environmental conditions, such as a desert region or a coastal region. In these climatic and environmental conditions, changes in wind direction and wind speed are violent and frequent and even storms and typhoons often occur. Accordingly, the wind-power generation system is easily operated under an over-speed condition so that the system is easily damaged due to the generated too-high voltage.
Reference is made to FIG. 1 which is a circuit block diagram of a prior art redundant electrical brake and protection system for electric generators. The prior art redundant electrical brake and protection system for electric generators is published with a publication number (CN101087122A) by State Intellectual Property Office (SIPO). The redundant protection system includes a system wherein two energy dissipation paths are consolidated. One path includes the generator side converter 111; the other path includes the dump load resistor 221. The generator side converter 111 can also be designed to accommodate up to rated output power rating for the generator 101, while the dump load resistor 221 is sized to provide the additional needed braking power.
The wind turbine control unit 190 makes a determination regarding availability of the generator side converter 111. If the generator side converter 111 is not available, the wind turbine control unit 190 provides for engaging the braker unit 105. If the generator side converter 111 is available, a determination is made by the converter control unit 140 regarding the required amount of braking power. If the required braking power is less than the rated output power of the generator 101, the converter control unit 140 provides for dissipating power in the generator side converter 111. If the required braking power is greater than the rated output power of the generator 101, the dump load resistor 221 is operated.
Accordingly, it is desirable to provide a wind-power generation system with an over-speed protection and a method of operating the same to provide an AC crowbar or a DC chopper to consume superfluous energy outputted from the generator, thus providing an over-load operation to brake the wind turbine when the wind turbine operates under an abnormal speed; even a fuse is disconnected to isolate the generator.